Australia has an estimated 57 million wild kangaroos, or nearly three times the human population, which damage crops and property and compete with livestock for food and water.

Despite being featured on the nation’s coat of arms, Australia culls millions of kangaroos each year. But the number of sturdy marsupials keeps increasing.

The problem is prominent around Canberra, where five years of drought have seen more kangaroos move into the suburban fringes looking for feed and becoming traffic hazards for commuters.

Kangaroos are the biggest animal risk to motorists in Australia, accounting for 70 percent of animal-related car accidents in 2004.

Grasslands and native forest around Canberra are home to the highest density of kangaroos in the country, with estimates of between 450 and 500 eastern gray kangaroos per square kilometer.

In Canberra, a city of about 300,000 people, kangaroos were responsible for 600 car accidents in 2004.

The local government that administers Canberra has now announced a scientific trial of contraceptives, which will be added to the grass in low-lying areas where the animals graze.

“It is hoped that eventually, the kangaroos will be administered with the fertility control agent through their food,,” the local minister responsible for the trial, John Hargreaves, said in a statement.

A decision to kill 800 kangaroos around Canberra two years sparked uproar and protests from animal rights groups, prompting the local government to look at alternatives.

Authorities in the past have trialed vasectomies for male kangaroos and slow release contraceptive implants for female, but both methods proved unworkable.